Many personal care products currently available to consumers are directed primarily to improving the health and/or physical appearance of the skin, hair, or nails. Among these skin, hair, or nail care products, many are directed to delaying, minimizing or even eliminating skin, hair, or nail changes typically associated with the aging or the environmental damage to human skin, hair, or nails. Numerous compounds have been described in the art as being useful for regulating skin, hair, or nail condition.
Skin, hair, and nails are subject to insults by many extrinsic and intrinsic factors. Extrinsic factors include ultraviolet radiation (e.g., from sun exposure), environmental pollution, wind, heat, low humidity, harsh surfactants, abrasives, and the like. Intrinsic factors include chronological aging and other biochemical changes from within the skin, hair, or nails. Whether extrinsic or intrinsic, these factors result in visible signs of skin, hair, and nail aging and environmental damage (e.g., such as sunlight damage, smoke damage, and damage from pollutants such as nitrogen oxides, sulfur oxides, ozone, and metals such as lead). To many people, the loss of the attractiveness of skin, hair, or nails is a reminder of the disappearance of youth. As a result, the maintenance of a youthful appearance has become a booming business in youth-conscious societies. Numerous products and treatments are available in various forms to help maintain the appearance of younger hair, skin, and nails.
Extrinsic or intrinsic factors may result in the thinning and general degradation of the skin, hair, or nails. For example, as the skin, hair, and nails naturally age, there is a reduction in the cells and blood vessels that supply the skin, hair, or nails. There is also a flattening of the dermal-epidermal junction which results in weaker mechanical resistance of this junction. See, for example, Oikarinen, “The Aging of Skin: Chronoaging Versus Photoaging,” Photodermatol. Photoimmunol. Photomed., vol. 7, pp. 3-4, 1990.
A large number of skin, hair, and nail care actives are known in the art and used to improve the health and/or cosmetic appearance of the skin, hair, or nails. For instance, various peptides are included in skin, hair, and nail care compositions to provide skin, hair, or nail care benefits. However, not all peptides can provide the benefits desired.
For instance, C terminal serine residues can yield dipeptides which may not be dermopharmaceutically and/or cosmetically active or which may not be useful in preferred applications. For instance, dipeptides including, for example, lysine and serine (Lys-Ser) can have inadequate properties for many dermopharmaceutical and cosmetic applications. Thus, it would be desirable to provide personal care compositions comprising a dipeptide that can provide superior properties when compared to the corresponding Lys-Ser dipeptide.